I take it the OS is on the SSD? Do you have the latest firmware installed in the SSD?

As background: it sounds like periodically the boot volume goes missing. In the past that would mean testing / replacing hardware in the storage chain -- SATA cable, drive, motherboard controllers (switching controllers if your motherboard has more than one). But in the new era of SSD teething pains, updating the firmware is the place to start.

Thanks for the advice UberGerbil. To confirm, the OS is on the SSD. Looks like I am a firmware version or 2 behind for the SSD. Hopefully this resolves the issue, because I would hate to have to start trouble-shooting my hardware devices.